1. FIELD OF THE INVENTION
In visual monitors, and especially for use with computers and the like, it is often necessary to have the ability to display rows of letters, numbers and other symbols. To provide the ability for these displays it is sometimes convenient to utilize sweep signals other than the normal horizontal and vertical sweep signals utilized in television and the like. For example, three signal deflection systems are used in some monitors because a less expensive logic system is required.
2. DESCRIPTION OF THE PRIOR ART
In prior art structures, a third small signal can sometimes be superimposed, or added to, the relatively large vertical deflection signal with only a small loss of linearity. However, if the third signal being added to the vertical deflection signal is relatively large a substantial nonlinearity occurs in the prior art structures.
Another type of device which might provide the required deflection could be constructed by providing a third set of deflection coils in the yoke. In this fashion the various deflection coils could be matched to the power supplies and there might be no loss of linearity. However, this method of providing the deflection requires a substantial increase in the amount and complexity of the equipment and a resulting increase in the cost.